Physicians have used elastic ligating bands to treat lesions, including internal hemorrhoids and mucositis and for performing mechanical hemostasis. The object of such ligation is to position a ligating band, which is usually elastic, over the targeted lesion or blood vessel section by first stretching the band beyond its undeformed diameter and then drawing the tissue to be ligated within the band. Thereafter the band is released so that it contracts, applying inward pressure on the section of tissue caught within the band. The effect of the inward pressure applied by the band is to stop all circulation through the targeted tissue, thereby causing the tissue to die. The body then sloughs off the dead tissue and the tissue passes naturally through the body.
U.S. Pat. No. 5,398,844 to Zaslavsky et al. ("the Zaslavsky patent") and U.S. Pat. No. 5,356,416 to Chu et al. ("the Chu patent"), which are incorporated herein by reference, describe ligating band dispensing devices each including a substantially cylindrical support surface over which elastic ligating bands are stretched. The cylindrical support surface is typically attached to the distal end of an endoscope which is advanced into the body to a target area. A user then applies suction through the endoscope to draw the tissue to be ligated into the cylindrical support surface and releases a ligating band to contract around the tissue.
Previous ligating band dispensers allowed a user to dispense only a single ligating band at a time. That is, after a single ligating band was dispensed, if a user wanted to ligate another portion of tissue, the user would remove the device from the patient's body, load a new ligating band on the device and reinsert the device to the desired area within the patient's body. The devices of the Zaslavsky and Chu patents allow a user to place several ligating bands at desired locations without removing the device from the patient's body to reload ligating bands. However, the Zaslavsky patent teaches the use of multiple strings to deploy the multiple bands (i.e. a separate pull string for each band), while the Chu patent teaches a ligator including multiple housing and piston segments to deploy the multiple bands.
U.S. Pat. No. 5,624,453 to Ahmed shows a device in which multiple cords 103 extend from a line element 105 to engage each of a plurality of ligating bands 50. Specifically, each of the cords 103 includes a plurality of knots 109 which are located proximally of each band 50 so that, when the line 105 is drawn proximally, each of the cords 103 is drawn proximally with one knot 109 on each cord 103 being moved distally an equal distance. Each of the knots 109 is substantially equally spaced about the circumference of the adapter 102 so that the force applied via the line 105 is distributed around the circumference of each of the bands 50 and an incrementally increasing amount of slack ensures that when the distal most remaining band 50 is deployed, none of the remaining bands is moved toward the edge of the adapter 102.
However, the multiple cords 103 extend distally across the field of vision of the endoscope impairing the vision of the operator. In addition, these symmetrically distributed cords 103 cause the line 105 to extend substantially centrally through the lumen of the endoscope, thereby limiting the operator's ability to use this lumen to operate other devices. Finally, as seen in FIG. 18, the cords 103 extend within the adapter 102 in a substantially cone shaped form, coming together at the connector 106. This may impede the drawing of lesion tissue into the adapter 102 under suction or, alternatively, may result in unintended deployment of the bands 50 as the tissue drawn into the adapter 102 pushes the connector 106 proximally. Finally, assembling a device as described in this patent can be very labor intensive--requiring proper placement of all of the multiple cords 103 and the corresponding slack segments with each of the cords being arranged so that the knots 109 are properly positioned with respect to the bands 50.